Heretofore, a large number pearlescent pigments and metal pigments having the shape of leaf, when incorporated into coating compositions etc., form coatings of design based on brightness by uniformly dispersing flaky pigment particles in coating layers. Recently, the development of various flaky pigments of design having brightness like plating is advanced by allowing flaky pigment particles represented by leafing aluminum flake pigment to float on the surface of a coating (leafing properties or plane orientation) to further improve the brightness of the coating. For example, with respect to metal pigments, a pigment comprising flake copper powder coated with stearic acid (JP-A 8-188731) and a pigment comprising aluminum flakes whose surface has been treated with alkyl phosphates (JP-A 11-57605) have been proposed as pigments having leafing properties.
Further, with respect to pearlescent pigments, a resin film comprising pearlescent pigments coated with a silane compound has been proposed (JP-A 7-62151). This silane coating pigment was used to raise leafing properties and compatibility between pigment particles and resin in the resin film.
Among these known flaky pigments, there are pigments showing excellent characteristics in leafing properties, but the interlaminar adhesion between the pigment particles and the coated film is weak, and accordingly, there is a defect in durability when used as coatings. That is, even if the known flaky pigment particles float on the surface of the coating to achieve a desired design by brightness based on their leafing properties, the interlaminar adhesion between the flaky pigment particles and a clear coating coated thereon for the purpose of protection is so low that the clear coating is easily removed upon attaching and pulling a cellophane tape or the like. Thus, such pigments used in a coating fail to achieve durability required of the coating.
On one hand, it is also attempted that the adhesion between pigment particles and a clear coating layer is raised without reducing leafing properties by devising a coating technique in which just before coating, an organic solvent-type base coating containing a resin composition for coating is mixed with a dispersion of leafing aluminum flake pigments in an organic solvent (JP-A 11-128828).
On the other hand, pigments treated with phosphate compounds having perfluoroalkyl groups (JP-A 5-93153) or with silane compounds (JP-A 2-218603) or pigments treated simultaneously with these compounds having perfluoroalkyl groups and reactive organic silicon compounds (JP-A 8-217989) are also proposed, but both of the pigments are developed for the purpose of improving the water- and oil-repellency of the pigments, and these are pigments used mainly for cosmetics.